diff --git a/doc/classes/PathFollow2D.xml b/doc/classes/PathFollow2D.xml
index 61db34fb024..7444bfc23aa 100644
--- a/doc/classes/PathFollow2D.xml
+++ b/doc/classes/PathFollow2D.xml
@@ -26,6 +26,7 @@
 		</member>
 		<member name="progress_ratio" type="float" setter="set_progress_ratio" getter="get_progress_ratio" default="0.0">
 			The distance along the path as a number in the range 0.0 (for the first vertex) to 1.0 (for the last). This is just another way of expressing the progress within the path, as the offset supplied is multiplied internally by the path's length.
+			It can be set or get only if the [PathFollow2D] is the child of a [Path2D] which is part of the scene tree, and that this [Path2D] has a [Curve2D] with a non-zero length. Otherwise, trying to set this field will print an error, and getting this field will return [code]0.0[/code].
 		</member>
 		<member name="rotates" type="bool" setter="set_rotates" getter="is_rotating" default="true">
 			If [code]true[/code], this node rotates to follow the path, with the +X direction facing forward on the path.
diff --git a/doc/classes/PathFollow3D.xml b/doc/classes/PathFollow3D.xml
index b505c6ea8ba..bcd04d51ca2 100644
--- a/doc/classes/PathFollow3D.xml
+++ b/doc/classes/PathFollow3D.xml
@@ -36,6 +36,7 @@
 		</member>
 		<member name="progress_ratio" type="float" setter="set_progress_ratio" getter="get_progress_ratio" default="0.0">
 			The distance from the first vertex, considering 0.0 as the first vertex and 1.0 as the last. This is just another way of expressing the progress within the path, as the progress supplied is multiplied internally by the path's length.
+			It can be set or get only if the [PathFollow3D] is the child of a [Path3D] which is part of the scene tree, and that this [Path3D] has a [Curve3D] with a non-zero length. Otherwise, trying to set this field will print an error, and getting this field will return [code]0.0[/code].
 		</member>
 		<member name="rotation_mode" type="int" setter="set_rotation_mode" getter="get_rotation_mode" enum="PathFollow3D.RotationMode" default="3">
 			Allows or forbids rotation on one or more axes, depending on the [enum RotationMode] constants being used.
diff --git a/scene/2d/path_2d.cpp b/scene/2d/path_2d.cpp
index 282d14da5d5..c3768386e9f 100644
--- a/scene/2d/path_2d.cpp
+++ b/scene/2d/path_2d.cpp
@@ -378,9 +378,10 @@ real_t PathFollow2D::get_progress() const {
 }
 
 void PathFollow2D::set_progress_ratio(real_t p_ratio) {
-	if (path && path->get_curve().is_valid() && path->get_curve()->get_baked_length()) {
-		set_progress(p_ratio * path->get_curve()->get_baked_length());
-	}
+	ERR_FAIL_NULL_MSG(path, "Can only set progress ratio on a PathFollow2D that is the child of a Path2D which is itself part of the scene tree.");
+	ERR_FAIL_COND_MSG(path->get_curve().is_null(), "Can't set progress ratio on a PathFollow2D that does not have a Curve.");
+	ERR_FAIL_COND_MSG(!path->get_curve()->get_baked_length(), "Can't set progress ratio on a PathFollow2D that has a 0 length curve.");
+	set_progress(p_ratio * path->get_curve()->get_baked_length());
 }
 
 real_t PathFollow2D::get_progress_ratio() const {
diff --git a/scene/3d/path_3d.cpp b/scene/3d/path_3d.cpp
index 1f8f7cd54ce..dc030b6a0f3 100644
--- a/scene/3d/path_3d.cpp
+++ b/scene/3d/path_3d.cpp
@@ -461,9 +461,10 @@ real_t PathFollow3D::get_progress() const {
 }
 
 void PathFollow3D::set_progress_ratio(real_t p_ratio) {
-	if (path && path->get_curve().is_valid() && path->get_curve()->get_baked_length()) {
-		set_progress(p_ratio * path->get_curve()->get_baked_length());
-	}
+	ERR_FAIL_NULL_MSG(path, "Can only set progress ratio on a PathFollow3D that is the child of a Path3D which is itself part of the scene tree.");
+	ERR_FAIL_COND_MSG(path->get_curve().is_null(), "Can't set progress ratio on a PathFollow3D that does not have a Curve.");
+	ERR_FAIL_COND_MSG(!path->get_curve()->get_baked_length(), "Can't set progress ratio on a PathFollow3D that has a 0 length curve.");
+	set_progress(p_ratio * path->get_curve()->get_baked_length());
 }
 
 real_t PathFollow3D::get_progress_ratio() const {